Shock absorber for rotary drills



July 5, 1955 w T, ALLEN 2,712,435

SHOCK ABSORBER FOR ROTARY DRILLS Filed March 15, 1951 2 Sheets-Sheet l July 5, 1955 w. T. ALLEN 2,712,435

SHOCK ABSORBER FOR ROTARY DRILLS Filed March l5. 1951 s 2 Sheets-Sheet 2 Wa/fer 7. A//en INVEN TOR.

BY ,Qzwaaih MPM'.

I Attorneys ,the pistons.

2,7l2,435 Patented July 5, 1955 fr Y sce

SHOCK ABSGRBER FR RTARY DRILLS l alter T. Allen, Cuero, `rlex..

Application March 15, 1951, Serial No. 215,793

6 Claims. (Cl. Z55- 28) This invention relates to an improved device to attach a drill bit to a shank of the rotary type.

The object of this invention is to provide an improved device for attaching a drill bit on the end of a rotary shank, the device including in addition to a plunger pot action and yet permit displacement of the plunger with respect to the body in response to shocks occasioned by use of the bit.

Ancillary objectsand features of importance will become apparent to those skilled in the art in following the description of the illustrated form of the invention.

ln the drawings: t f

Figure l is a longitudinal sectional view ofthe device and taken substantially on the line l-l of Figure 3 and in the direction of the arrows;

Figure 2 is a sectional view similar to that ofFigure l but showingfthe plunger 'moved inwardly with respect to the body;

Figure 3 is a transverse sectional view taken on the line 3 3 of Figure l and in the direction of the arrows; Figure Ll'is an exploded perspective View of the component parts of the device, and;

Figure 5 is an exploded perspective view of one of in the accompanying drawings l have illustrated a body 19, a plunger l2, a coupling la, a cover la, a plurality' of pistons l and a plurality of springs 2i?. These components form the essential parts of the device and are seen individually in Figure 4 and in assembly in Figures l and 2.

The plunger l?. is provided with a threaded coupling 24 at its outer end and in the shank portion thereof, the threaded coupling 24 being adapted to connect to a conventional drill shank 26. The shank 27 of the plunger terminates in a head 2S which is located in the cover l and specifically, in the concavity 3l) defined in part by the cover 16 and by the top part of the body lll, the cover 16 being threaded as at 32 to a reduced part of the body lll and held fastened in place by additional locking means, preferably the set screws 34. Accordingly, the cover l5 constitutes a part of the body lll when the cover is assembled with the main body block.

There is an inwardly extending flange 36 provided at the top of the cover i6, this flange constituting a means of limiting the extent of outward movement of the plunger head 28 with respect to the body l@ inasmuch as the body supports the plunger in such a manner that the plunger is reciprocable with respect to the body. A conventional O ring type seal 38 is located in a groove formed in the liange 36 and arranged to contact the outer surface of the shank 27 of the plunger 12.

The coupling le is provided with internal threads 40 to which a conventional drill bit schematically indicated at 42 is adapted to fasten. Any suitable type of drill bit may be used in connection with the device, the choice being left within the prerogative of the user of the device and within his sound discretion. The upper end of the coupling l; threadedly connected to a skirt which is formed at the lower end of the body block and there is a seal 46 fastened at the junction of the coupling 14 and the main body block. When the coupling llt is connected with the main body block, it constitutes a part of the body.

The device is adapted to be used in connection with Shanks 26 which have central liquid conducting passage therein inasmuch as the piston l2 has a central passage d8 extending therethrough, the passage being in axial alignment with the bore 50 of a sleeve 55 which is iixed to the head 23 of the plunger as an axial extensien thereof. The body lil has a bore 52 therein and there is a counterbore 54 at the upper end of the bore 52, this counterbore receiving the sleeve 5S and the bore` 52, the bore Si) and counterbore being in axial alignment with the passage d8 to permit free flow of water therethrough.

The head 23 of the plunger l2 is provided with a plurality of chambers 56 arranged parallel to the longirudinal axis thereof. ln axial alignment with the chambers 5e and form-ed in the body lil, there are a plurality of chambers 5S, the latter chambers retaining a fluid of propt; choice, as oil, water or glycerin base lluids, which is to be used in connection with the hollow casings 6) which constitute a part of the pistons 1S. The easings are cylindrical and are lixed by conventional means within chambers S6 and are slidable in the chambers 53 .when the plunger is moved with respect to the. body lll. Each piston has a fluid chamber 62 in it and a closure 64 for the chamber, the closure having an orilice 66 therein which opens into the chamber d2 and also into the chamber 58. A conventional wiper 79 which may be made of leather, rubber or other suitable material, is fastened to the lower end of each casing and overlies Vthe Aouter wall of the closure 64 which is l, exposedn to the Vwalls of the lower chamber 58. v

" Means, for example the springs 2i), are provided between the body lil and the plunger l2 in order to constantly, yieldingly press the plunger l2 outwardly of the body to the limit of outward movement of the plunger occasioned by the presence of the flange 36 which constitutes a limiting stop. The springs 20 are preferably located in recesses 74 and 76 which are respectively formed in the body l@ and the plunger head in order to hold them centered in place within the device.

In operation the coupling threads 24 are applied to the existing threads of a standard drill shank 26. After a properly selected bit l2 is connected with a coupling ld, the drill is in readiness for operation. When the bit is jarred due to normal drilling operations, instead of the jar being transmitted abruptly to the shank 26, the shock is absorbed inasmuch as the body lll moves upwardly with respect to the plunger l2 causing the fluid in the chamber 53 to move through the restriction or orifice 66 into the chamber 62. This provides a dashpot action; however, the movement of the body with respect to the plunger is opposed by the springs 24. Accordingly, after the initial shock has been absorbed and the body lll moved upwardly with respect to the plunger i2, the springs 25 will return the body to its normal extended position.

Having described the invention, what is claimed as new 1. A device to hold a drill bit on a shank, said device comprising a body provided with a cavity, a plunger hav- 'ing means at one end adapted to fasten to a drill shank and a head at the opposite end which is disposed in said cavity, means adapted to fasten to a drill bit at the end of said body opposite from theV end of the body having said cavity, said body and said head having a plurality of aligned fluid chambers therein, casings fastened in the chambers in said head, said casings being slidably disposed in the chambers in said body, and said casings having orilices therein which open into the chambers in said body.

2. The combination ofV claim 1 and said plunger head Vhaving a sleeve extending therefrom, said body being provided with a liquid conducting bore, with a counterbore at one end arranged to receive said sleeve, the bore of said sleeve being in alignment with said first mentioned bore, and said plunger having a liquid passage in align- Ament with both of said bores.

3. A device to hold a drill bit on a shank, said device comprising a body provided with a cavity opening into Y one end thereof, a plunger having means at one end adapted to fasten to a drill shank and a head at the opposite end which is slidably disposed in said cavity, means adapted to fasten to a drill bit at the end of said body opposite from the end of the body having said cavity, said body and said head having aligned uid chambers therein, casings fastened in the chambers in said head, said casings being slidably disposed in the chambers in said body, and said casings having orifices therein which open into the chambers in said body, said body and said plunger having cooperating abutment surfaces for limiting the movement of said plunger outwardly of said body, and means yieldingly urging said plunger outwardly of said cavity to the limit of plunger movement outwardly of the cavity.

4. Inl a device for coupling a drill bit on a shank, a body member, a sleeve secured to said body member and constituting an extension'thereof, said sleeve having a reduced opening in the end remote from the body member providing an internal shoulder, a plunger having a head thereon reciprocably disposed in said sleeve, said head abutting said internal shoulder to limit the outward movement of said plunger from said body member, said body member and said head having aligned chambers therein, hollow casings mounted in some ofV the chambers Yin said head andY being slidably engaged in the bers urging said head toward said internal shoulder seating in the remaining aligned chambers, said casings having orice's therein opening into said body member chambers whereby the sliding movement of the casings will be resisted by fluid pressure within the chambers.

5. In a device for coupling a drill bit on a shank, a body member, a sleeve secured to said body member and constituting an extension thereof, said sleeve having a reduced opening in the end remote from the body member providing an internal shoulder, a plunger having a head thereon reciprocably disposed in said sleeve, said head abutting said inter-nal shoulder to 'limit the outward movement of said plunger from said body member, said body member and said head having aligned chambers therein, casings mounted in some of the chambers in said head and being slideably engaged in the aligned chambers in said body member, resilient members urgingsaid head toward said internal shoulder seating in the remaining aligned chambers, said casings constituting hollow pistons adapted to receive iuid, said casings having reduced orices opening into the body chambers .and including wipers contacting the Walls of said body chambers, said body chambers constituting uid cham# bers whereby sliding movement of the casings thereinto is resisted by uid pressure within the chamber.

6. In a device for coupling a drill bit to a shank, a

body having a cavity, a plunger provided with a head References Cited in the tile offr'this patent UNITED STATES lPATENTS 1,785,559 Ponti Dec. 16, 1930 1,902,421 Rawdon et al Mar. 21, 1933 2,023,527 Johansen Dec. 10, 1935 2,240,519 Reed May 6, 1941 2,263,770 Greve Nov. 25, 1941 2,325,132 1943 Haushalter et al. July 27, 

